1. Field of the Invention
The present invention relates to a method of recording information on a recording medium and erasing the recorded information.
2. Description of Related Art
There is known an information recording and reproducing apparatus capable of recording information on an optical disc, such as a DVD-R/RW and the like, and capable of reproducing and erasing the recorded information. So far, additional recording was performed by a method, such as a UDF (Universal Disk Format) and a multi-session, as for an additionaly-recordable-type recording medium capable of recording information only once, like a DVD-R. In the method, when the recorded information is erased, newest file management information is wholly utilized by additionally recording changed file management information in a new area while a last file management information area is left as it is (see Japanese Patent Application Laid-open under No. 2002-324383).
Namely, a data area is left as it is without any change, and data of the file is not erased from the disc until the data area is overwritten by other files. It takes a long time to completely erase all the contents of the file in the data area, which is not efficient. Therefore, such the method is adopted.
However, in the above-mentioned method of additionally recording the data, the old recorded data remains on the disc, and the information in the last file management information area can be also read. Therefore, even after an erasing command is executed, the recording data which is apparently erased can be actually readout from the information recording medium by reading the information in the old file management information area before the erasure. In addition, even if such file management information before the erasure is deleted, the recording data itself remains on the disc. Therefore, it is possible to restore the recorded data by tracing the portion thereof. Like this, in the conventional erasing method, it is impossible to erase the recorded data in a manner completely unreadable. Thus, there occurs probability that the recorded data which was apparently erased, such as important data including personal information and the like, is restored and watched by the above-mentioned method.
As a method of completely erasing the data which is recorded on the recording medium capable of recording the information only once, there are known a method of destroying the recording medium itself, and a method of making it impossible to read out all the file management information are a by physically overwriting it. However, in those methods, the data other than the data to be erased cannot be read out, either. Further, when the method of overwriting all the file management information area is utilized, it problematically takes a long time for the process.